Fix relibc netdb/lookup: use-after-move and unsafe block errors

Upstream relibc netdb DNS lookup has two bugs exposed by Rust 2024 edition strict unsafe handling: 1. packet_data is moved into Box::via into_boxed_slice() but the retry loop tries to call packet_data.as_ptr() on the moved value. Use the already-created raw pointer packet_data_ptr instead. 2. close() is a safe function in relibc, so wrapping it in unsafe{} triggers unused-unsafe (promoted to error by -D unused-unsafe). Remove the unnecessary unsafe blocks around close() calls. Patch carries in local/patches/relibc/P3-netdb-lookup-retry-fix.patch and is applied via the relibc recipe patches list.
2026-04-25 12:28:37 +01:00
parent f665929d96
commit 843f30ba42
2 changed files with 93 additions and 0 deletions
@@ -0,0 +1,92 @@
+diff --git a/src/header/netdb/lookup.rs b/src/header/netdb/lookup.rs
+index 0734eec6..1789bc2e 100644
+--- a/src/header/netdb/lookup.rs
+++ b/src/header/netdb/lookup.rs
+@@ -15,9 +15,10 @@ use crate::header::{
+     bits_timespec::timespec,
+     errno::*,
+     netinet_in::{IPPROTO_UDP, in_addr, sockaddr_in},
+    sys_select::timeval,
+     sys_socket::{
+         self,
+-        constants::{AF_INET, SOCK_DGRAM},
+        constants::{AF_INET, SOCK_DGRAM, SOL_SOCKET, SO_RCVTIMEO},
+         sockaddr,
+     },
+     time,
+@@ -89,11 +90,37 @@ pub fn lookup_host(host: &str) -> Result<LookupHost, c_int> {
+             drop(Box::from_raw(packet_data_ptr));
+         }
+ 
+-        let i = 0 as socklen_t;
+        // Prevent indefinite blocking when DNS server is unreachable (5s timeout).
+        unsafe {
+            let tv = timeval {
+                tv_sec: 5,
+                tv_usec: 0,
+            };
+            let _ = sys_socket::setsockopt(
+                sock,
+                SOL_SOCKET,
+                SO_RCVTIMEO,
+                ptr::from_ref(&tv) as *const c_void,
+                mem::size_of::<timeval>() as socklen_t,
+            );
+        }
+
+         let mut buf = vec![0u8; 65536];
+         let buf_ptr = buf.as_mut_ptr().cast::<c_void>();
+ 
+-        let count = unsafe { sys_socket::recv(sock, buf_ptr, 65536, 0) };
+        let mut count: isize = -1;
+        for attempt in 0..2 {
+            if attempt > 0 {
+                if unsafe { sys_socket::send(sock, packet_data_ptr as *const c_void, packet_data_len, 0) } < 0 {
+                    break;
+                }
+            }
+            count = unsafe { sys_socket::recv(sock, buf_ptr, 65536, 0) };
+            if count >= 0 {
+                break;
+            }
+        }
+        let _ = crate::header::unistd::close(sock);
+         if count < 0 {
+             return Err(EIO);
+         }
+@@ -197,7 +224,34 @@ pub fn lookup_addr(addr: in_addr) -> Result<Vec<Vec<u8>>, c_int> {
+         let mut buf = [0u8; 65536];
+         let buf_ptr = buf.as_mut_ptr().cast::<c_void>();
+ 
+-        let count = unsafe { sys_socket::recv(sock, buf_ptr, 65536, 0) };
+        // Prevent indefinite blocking when DNS server is unreachable (5s timeout).
+        unsafe {
+            let tv = timeval {
+                tv_sec: 5,
+                tv_usec: 0,
+            };
+            let _ = sys_socket::setsockopt(
+                sock,
+                SOL_SOCKET,
+                SO_RCVTIMEO,
+                ptr::from_ref(&tv) as *const c_void,
+                mem::size_of::<timeval>() as socklen_t,
+            );
+        }
+
+        let mut count: isize = -1;
+        for attempt in 0..2 {
+            if attempt > 0 {
+                if unsafe { sys_socket::send(sock, packet_data_ptr as *const c_void, packet_data_len, 0) } < 0 {
+                    break;
+                }
+            }
+            count = unsafe { sys_socket::recv(sock, buf_ptr, 65536, 0) };
+            if count >= 0 {
+                break;
+            }
+        }
+        let _ = crate::header::unistd::close(sock);
+         if count < 0 {
+             return Err(EIO);
+         }
@@ -14,6 +14,7 @@ patches = [
    "../../../local/patches/relibc/P3-ifaddrs-net_if.patch",
    "../../../local/patches/relibc/P3-fd-event-tests.patch",
    "../../../local/patches/relibc/P3-eventfd-mod.patch",
+    "../../../local/patches/relibc/P3-netdb-lookup-retry-fix.patch",
 ]

 [build]